This invention relates to the protective long term storage of flat collectible items, and more particularly concerns a protective case for the storage of rare postage stamps and paper currency.
U.S. patent application Ser. No. 07/468,052, filed 01/22/90 describes a plastic holder case, constructed of two halves, for protectively securing and authenticating sports cards such as baseball cards. The holder has a specialized design whereby the enclosed card disposed in a first holding zone, is not squeezed into contact with the plastic holder, but is instead movable within the holder. This feature prevents the sticking of the card to the plastic during long term archival storage. A second holding zone within the holder accommodates documentary indicia. The two halves of the holder are cohesively bonded together, preferably by sonic welding techniques to encapsulate the enclosed card. Such cohesive bonding method avoids the use of solvent-based adhesives whose solvents could adversely affect the card during long term storage. To further enhance archival storage characteristics, the halves of the case are swept with an inert gas or are disposed in a vacuum chamber during the bonding process. This prevents the retention of any aggressive gaseous species within the sealed holder case.
The aforesaid plastic holder case would appear to be well suited for retaining other valuable flat items, where the sealed nature of the case would desirably protect the item and provide authentication. However, it has been found that, in the case of postage stamps, paper currency, and other thin, light-weight articles, the sweeping gas movement or sonic vibration during the sealing process causes the article to "float" out of the holder during the bonding process.
It is accordingly an object of the present invention to provide a transparent case for flat, light-weight collectible items.
It is another object of this invention to provide a case as in the foregoing object adapted for sealing by cohesive bonding techniques.
It is a further object of the present invention to provide a case of the aforesaid nature which prevents movement of said light-weight item by gaseous current during said cohesive bonding.
It is a further object of the present invention to provide a case of the aforesaid nature which is stackable with other cases of the same construction.
It is a still another object of this invention to provide a case of the aforesaid nature of rugged, durable construction amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.